Volume and Surface Area

It is called an icosahedron because it is a polyhedron that has 20 faces (from Greek icosa- meaning 20)

When we have more than one icosahedron they are called icosahedra

When we say "icosahedron" we often mean "regular icosahedron" (in other words all faces are the same size and shape), but it doesn't have to be - this is also an icosahedron, even though all faces are not the same.

20-Sided Dice? Yes! An icosahedron that has 20 equal faces has an equal chance of landing on any face.